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The main goal of this study consists of the development of new asphalt mixes, based on industrial waste materials as replacement of natural aggregates. To achieve this purpose, a new characterisation of these pavements was proposed so to verify that the new mix has good mechanical performance without any detrimental impact to the environment.<p>This characterisation was divided in three distinct steps:<p>• a physical and chemical characterisation of the different constituents of asphalt concrete, as well the natural materials as the industrial waste considered as potentially secondary aggregates,<p>• a study of the bitumen-aggregate interface by means of two techniques: a qualitative method (scanning electron microscope) and a quantitative one (nanoindentation)<p>• an evaluation of the mechanical performance of mixes containing industrial waste, before and after recycling, by means of four standard road-engineering tests.<p>The numerous results allowed to put in evidence the possibility to reuse some industrial waste materials in asphalt concrete. In addition, this characterisation containing both chemical and mechanical aspects, at the microscopic and macroscopic scales, would permit the transposition of this study to the whole of asphalt concrete./<p>Le principal objectif de ce travail consiste en le développement de nouveaux mélanges bitumineux utilisant des déchets industriels en tant que remplacement des matériaux naturels. Pour ce faire, une nouvelle caractérisation de ces revêtements a été proposée afin de vérifier que le nouveau revêtement obtenu présente de bonnes performances mécaniques tout en évitant un impact environnemental néfaste.<p>Cette caractérisation a été scindée en trois étapes distinctes :<p>•\ / Doctorat en sciences appliquées / info:eu-repo/semantics/nonPublished

M. Tech. Civil Engineering. / Evaluates various laboratory test methods to assess rutting potential in the hot-mix asphalt (HMA) and the effects of compaction methods. To achieve this objective, rutting potential of HMA samples prepared and compacted in the laboratory, and in the field was evaluated using different laboratory test methods under a range of temperatures and loads.

This diploma thesis deals with the design of repairs to the asphalt concrete facing of the upper reservoir of the pump-storage power station Dlouhé Strána. The first part summarizes the knowledge about asphalt concrete facings, experience from foreign constructions and a description of the damage on this hydraulic structure. The second part defines the variants of repairs and the selection of the most suitable on the basis of decision analysis.

In this thesis, nondestructive surface wave measurements are presented for characterization of dynamic modulus and layer thickness on different pavements and cement concrete slabs. Air-coupled microphones enable rapid data acquisition without physical contact with the pavement surface. Quality control of asphalt concrete pavements is crucial to verify the specified properties and to prevent premature failure. Testing today is primarily based on destructive testing and the evaluation of core samples to verify the degree of compaction through determination of density and air void content. However, mechanical properties are generally not evaluated since conventional testing is time-consuming, expensive, and complicated to perform. Recent developments demonstrate the ability to accurately determine the complex modulus as a function of loading time (frequency) and temperature using seismic laboratory testing. Therefore, there is an increasing interest for faster, continuous field data evaluation methods that can be linked to the results obtained in the laboratory, for future quality control of pavements based on mechanical properties. Surface wave data acquisition using accelerometers has successfully been used to determine dynamic modulus and thickness of the top asphalt concrete layer in the field. However, accelerometers require a new setup for each individual measurement and are therefore slow when testing is performed in multiple positions. Non-contact sensors, such as air-coupled microphones, are in this thesis established to enable faster surface wave testing performed on-the-fly. For this project, a new data acquisition system is designed and built to enable rapid surface wave measurements while rolling a data acquisition trolley. A series of 48 air-coupled micro-electro-mechanical sensor (MEMS) microphones are mounted on a straight array to realize instant collection of multichannel data records from a single impact. The data acquisition and evaluation is shown to provide robust, high resolution results comparable to conventional accelerometer measurements. The importance of a perfect alignment between the tested structure’s surface and the microphone array is investigated by numerical analyses. Evaluated multichannel measurements collected in the field are compared to resonance testing on core specimens extracted from the same positions, indicating small differences. Rolling surface wave measurements obtained in the field at different temperatures also demonstrate the strong temperature dependency of asphalt concrete. A new innovative method is also presented to determine the thickness of plate like structures. The Impact Echo (IE) method, commonly applied to determine thickness of cement concrete slabs using an accelerometer, is not ideal when air-coupled microphones are employed due to low signal-to-noise ratio. Instead, it is established how non-contact receivers are able to identify the frequency of propagating waves with counter-directed phase velocity and group velocity, directly linked to the IE thickness resonance frequency. The presented non-contact surface wave testing indicates good potential for future rolling quality control of asphalt concrete pavements. / <p>QC 20170209</p>

This study was carried out to evaluate the use of heated reclaimed asphalt pavement materials with emulsion and the use of hot mix asphalt with wax (Sasobit) as base course materials. Mixes with lower than optimum and optimum emulsion, as well as with heated reclaimed asphalt pavement material and optimum emulsion were made; also, mixes with conventional asphalt binder and those with asphalt binder and Sasobit were produced at relatively lower temperatures. These mixes were tested for workability, and all but one of the mixes were used for preparation of approximately 0.9 m (35 inches) by 0.9 m (35 inches) 0.125 m (5 inches) slabs. The rates of densification during the compaction of these slabs were compared. Samples cored from the slabs were tested for stiffness, and dry retained tensile strengths. The results showed that heating of reclaimed asphalt pavement material can improve the dispersion as well as densification significantly. The use of asphalt binder was found to be beneficial in improving strength and stiffness, and the use of Sasobit helped to achieve almost similar workabilities and compactabilities at lower temperatures, as compared to those of hot mix asphalt with neat asphalt binder. No significant difference was found between the modulus of the Sasobit and hot mix asphalt samples. The dispersion of asphalt binder seemed to improve with the use of Sasobit at lower mixing temperature. A field project is recommended for evaluating performance of emulsion mixes with heated reclaimed asphalt pavements and asphalt binder mixes with Sasobit.

As new materials are developed and further concerns on green alternatives and serviceability arise, understanding material behavior during the entire span of their lifetime becomes crucial to engineering applications. Moreover, many problems display a significant dependence to time and loading effects which, by varying across multiple time scales, require material models that incorporate these effects into any valid characterization and prediction. This dissertation aims at proposing a new approach to analyze and predict viscoelastic materials that deteriorate during multiple loading conditions. The model is constructed from mechanical and mathematical basis while satisfying physical laws. In this work, the proposed constitutive law is used for the analysis of the mechanical properties of ice. The mechanical behavior, biaxial envelop and multiple loading types demonstrate the validity of the model when compared to experimental results and other ice models available in the literature. A rigorous calibration scheme for the viscoelastic and damage parameters is also presented. Moreover, as material deterioration or damage is modeled in standard Finite Elements software, it is commonly known that computational results can be dependent on the spatial discretization or mesh. That is, damage zone and energy dissipation are dependent on the selection of the mesh yielding a disappearing damage zone and energy dissipation upon refinement. This non-physical behavior is corrected by the novel regularization approach proposed in this document, which introduces a length scale of the material and produces results that are no longer sensitive to the mesh selection. The nonlocal damage model is finally used in the analysis of asphalt concrete viscoelastic behavior and cracking prediction. As presented in the ice case, a rigorous calibration approach is presented first followed by the validation to experimental data available in the literature under different loading conditions. The coupled viscoelastic and damage model is compared to other model and their Finite Elements implementations are highlighted in terms of computational efficiency. A nonlinear coupled system for solving this problem is programmed as a User Element in a commercial Finite Element analysis software.

This dissertation presents the development of an anisotropic viscoplastic continuum damage model to describe the permanent deformation of asphalt pavements. The model is developed to account for several phenomena that influence the permanent deformation of Asphalt Concrete (AC) at high temperatures. These phenomena include strain rate dependency, confining pressure dependency, dilation, aggregate friction, anisotropy, and damage. The model is based on Perzyna's theory of viscoplasticity with Drucker-Prager yield function modified to account for the microstructure anisotropy and damage. A parametric study was conducted to study the effect of key factors such as inherent anisotropy and damage on the model response. A preliminary investigation was conducted to demonstrate the capabilities of the model and its sensitivity to changes in the microstructure distribution and loading conditions. The model was used to describe laboratory experimental measurements obtained from the Federal Highway Administration (FHWA) Accelerated Loading Facility (ALF). The model had a good match with these experimental measurements. In particular, using the damage parameter, the model was able to capture the point at which AC experienced tertiary creep in a static creep test. A comprehensive experiment was conducted to systematically determine the model parameters and the evolution laws that describe AC hardening, anisotropy, and damage. The experiment consisted of a set of compressive triaxial strength tests conducted at three confining pressures and five strain rates. Based on these experimental measurements, the model was modified to include a nonassociated flow rule. The model was shown to capture the experimental measurements very well. Furthermore, an experiment was conducted to capture and characterize damage evolution in AC due to permanent deformation. AC specimens were loaded using a triaxial compression setup to four predefined strain levels at three confining pressures. X-Ray computed tomography and image analysis techniques were used to capture and characterize the evolution of cracks and air voids in the deformed specimens. Damage was found to be a localized phenomenon in the sense that there exists a critical section in an AC specimen that is mainly responsible for failure. The results of the damage experiment supported the damage evolution function proposed in the viscoplastic model.

The failure of longitudinal construction joints is one of the critical factors causing accelerated pavement deterioration. Poor-quality longitudinal construction joints are often characterized by a difference in elevation between adjacent lanes or by unraveling of the hot mix asphalt (HMA). Current wave-based non-destructive testing (NDT) methods are efficient and economical for the evaluation of material properties. In this thesis, an innovative surface wave testing technique for condition assessment of longitudinal construction joints in asphalt pavements is presented. This method enables reduction of the number of cores required for large-strain testing and provision of a more uniform quality assessment of longitudinal joints as well as the relative condition of the asphalt pavements. The technical development is based on a theoretical study of the wave attenuation mechanisms and on the reported deficiencies in current seismic wave-based methods. Traditionally, the use of ultrasonic testing to determine small-strain elastic property for asphalt concrete was uniquely based on the measurement of wave velocity. However, isolated use of wave velocity does not provide complete information of the materials strength because of the different variables that affect the strength-velocity relationship. Therefore, it is necessary to complement velocity data with independent information such as the change in attenuation and frequency content of the propagating pulse. The existing deficiencies in current seismic wave-based methods were addressed to improve reliability, accuracy and consistency for asphalt concrete material characterization in the laboratory and in the field. Refined and improved signal processing techniques were used to overcome the shortcomings in the existing wave-based methods that contribute to uncertainties in the interpretation of test results. To capture more information from a wave, the signal was analyzed in the time and frequency domains. The basic analyses included a simple method such as peak to peak amplitude of the first cycle of arriving wave, and complex methods such as maximum magnitude and area of corresponding frequency spectrum through Fourier transform. A novel approach based on wavelet transform of the signal was presented, which provides an alternative method to determine wave characteristics. Material characterization tests (experiment Phase I) were carried out to study the relationship between the wave characteristics obtained from UPV test and the quality of the asphalt concrete specimens prepared in the laboratory. The specimens were identical in terms of aggregate and asphalt binder ratio, but varying in volumetric properties produced by different compaction efforts. The specimen quality was determined using two methods: 1) the traditional method using density measurement and 2) an innovative approach using dynamic modulus which is recommended by the Federal Highway Administration (FHWA) for use as a fundamental material property for characterizing Superpave mixes (Witczak, et al., 2002; Bonaquist et al., 2003; Christensen et al., 2004). The measured wave characteristics showed excellent correlations (R2 > 0.9) with the fundamental properties of the mix. The results revealed that the wave amplitude parameters as the condition index have the potential to provide a reliable assessment of the quality of HMA mixtures. The finding is very critical to moving the technology forward in the right direction, and form an important basis for the experiment Phase II. Experiment Phase II investigated the feasibility and effectiveness of using the wave characteristics identified in experiment Phase I to assess the condition of longitudinal construction joints. Particular attention was given to examining the sensitivity of the wave-based technique to different types of construction joints. For this purpose, three types of construction joints (good, fair and poor) were fabricated in the laboratory and identified using the wave-based technique. The research was intended to develop a suitable test procedure for condition assessment the longitudinal joints in asphalt pavement in the field. The data from experiment Phase II revealed that the wave-based technique enables assessment of not only the quality of different types of longitudinal construction joints but also the relative condition of asphalt pavements.